Internationalization:

To allow representation of the world’s languages, HTML 4 adopts the Universal Character Set as its character set. Previous versions of HTML were restricted to ISO-8859-1, a character set that only handled some western European languages.

The Universal Character Set is character-by-character equivalent to Unicode and contains characters for almost all of the world’s languages.

The lang and dir attributes are new in HTML 4.0 and apply to almost all elements. These attributes allow authors to specify the language and directionality of text.

The BDO element allows authors to override the bidirectional algorithm used when right-to-left text such as Hebrew is presented.

Style Sheets:

The new id, class, and style attributes allow style information to be attached to specific elements. The link and style elements have new type and media attributes for specifying the style sheet language and target media, respectively.

Client-side Scripting:

The noscript element added in HTML 4.0 which provides alternate content for browsers with client-side scripting disabled or not supported.

The script element now includes attributes for specifying the scripting language, embedding an external script, and deferring execution of a script.

A number of new event attributes have been added to enable execution of a script upon events such as the user clicking an element, pressing a key, moving the mouse over an element, or changing the value of a form control etc.

Frames:

Ability to divide a window into multiple frames and using different document into each frame is very important feature in HTML 4.0.

Ability to handle old browsers is also added by introducing <noframe> element.

Advanced Tables:

The simple table model of HTML 3.2 is expanded in HTML 4 to include row and column groups.

The use of row groups (thead, tfoot, tbody) allows visual browsers to render static header and footer rows with scrollable body rows, thus improving the readability of large tables.